merge(glittershark/achilles): Subtree import at 'b93268085a'

Imported from https://github.com/glittershark/achilles/

git-subtree-dir: users/glittershark/achilles
git-subtree-mainline: 4d193f2395
git-subtree-split: b93268085a
Change-Id: I64a583b454bbe03e20358ad7808939a4cbc212ba

users/glittershark/achilles/src/commands/eval.rs

@@ -0,0 +1,32 @@
+use clap::Clap;
+
+use crate::codegen;
+use crate::interpreter;
+use crate::parser;
+use crate::tc;
+use crate::Result;
+
+/// Evaluate an expression and print its result
+#[derive(Clap)]
+pub struct Eval {
+    /// JIT-compile with LLVM instead of interpreting
+    #[clap(long)]
+    jit: bool,
+
+    /// Expression to evaluate
+    expr: String,
+}
+
+impl Eval {
+    pub fn run(self) -> Result<()> {
+        let (_, parsed) = parser::expr(&self.expr)?;
+        let hir = tc::typecheck_expr(parsed)?;
+        let result = if self.jit {
+            codegen::jit_eval::<i64>(&hir)?.into()
+        } else {
+            interpreter::eval(&hir)?
+        };
+        println!("{}", result);
+        Ok(())
+    }
+}